1. Field of the Invention
This invention relates to a process for the manufacture of a cutback of a mixture of bitumen and rubber and to a cutback thus obtained.
2. Description of the Prior Art
Cutbacks of mixtures of bitumen and rubber can suitably be used, e.g. for surface dressings on roads, in particular on sites exposed to high stresses caused by heavy turning traffic. The cutback is sprayed at the road surface whereafter the surface is covered with chippings, which are preferably precoated with bitumen. The volatile solvent of the cutback, e.g. kerosine, then slowly evaporates and the chippings should show a good retention to the road surface, even under the above-mentioned heavy conditions.
A drawback of such cutbacks is the tendency to form a skin of rubbery material at the upper surface, which skin prevents the further evaporation of the solvent. This causes loss of most of the chippings under said heavy conditions.
The treatment of a mixture of bitumen and rubber with a peroxide in order to prepare cross-linked homogeneous bitumenous compositions which are suitable for e.g. road-building is disclosed in U.S. Pat. No. 3,963,659. The use of cutbacks of these mixtures and the above-described problem encountered with such cutbacks are not mentioned.